Idiopathic pulmonary fibrosis (IPF) is one of the most fatal lung diseases with high mortality and very limited treatment options. Increased production of collagen is found in IPF patients? lung. Unfortunately current FDA- approved treatments do not stop disease progression. In vitro and in vivo proof-of-concept studies have been completed by our company and demonstrated that inhibiting peptidyl-prolyl-isomerase can be an effective strategy to reduce collagen production and eventual fibrotic lung remodeling. Therefore, we have designed an exploratory library of novel compounds based on 4-amino acid backbone to exploit this therapeutic strategy. Out of the first eight of the 24 novel compounds, one has already shown highly active inhibition of collagen production by human fibroblasts. This Phase 1 SBIR proposal will further develop this technology by identifying the best compound and establishing its therapeutic proof-of-concept in in vitro and in vivo modeling (Aim 1) and by identifying and refining the best compound identified from the Aim 1 pre-existing library for the optimal PK profile (Aim2). When these milestones are accomplished, these new compounds are anticipated to become ready for entering the pre-IND phase of therapeutic development.